The present invention relates to an exposing device and an image forming apparatus using the exposing device.
A general electrophotographic image forming apparatus (for example, a printer, a copier, a facsimile machine or a combined machine) uses an exposing device such as an LED head that exposes a uniformly charged surface of a photosensitive drum to form a latent image.
The exposing device includes, for example, an LED array mounted to a substrate and a rod lens array held by a lens holder. The substrate is mounted to the lens holder so that the LED array faces the rod lens array. The surface of the photosensitive drum is located on a focusing position of the rod lens array. Lights emitted by the LED array pass the rod lens array, and are focused on the surface of the photosensitive drum to form a latent image.
Since the lens holder has a function to support the substrate and the lens array, the lens holder is generally made of aluminum having rigidity (see, for example, Patent Document No. 1). Further, the lens holder has substrate abutting surfaces which are finished with high accuracy. The substrate is held by the lens holder in such a manner that both end portions of the substrate (in a widthwise direction thereof) contact the substrate abutting surfaces.
Patent Document No. 1: Japanese Laid-open Patent Publication No. 2002-154235 (paragraph 0006, FIG. 1)
In this regard, there is a need for a technique capable of ensuring electrical insulation between the substrate and the lens holder made of metal.